1. Field of the Invention
This invention relates generally to a method and apparatus for dispensing a use solution and more particularly to a dispensing system using a diluent boost pump.
2. Description of the Prior Art
Transportation costs associated with an aqueous diluent portion of a formulated aqueous product can be a significant part of the cost of aqueous liquid products as used at a use location. Products, such as sanitizing or cleaning solutions, when used in large amounts can be expensive to use due to transportation costs associated with the aqueous portion. For this reason, many commodity liquid products are shipped from the manufacturers as an aqueous concentrate, an aqueous alcoholic concentrate or as a viscous concentrate to be diluted in a dispenser with an aqueous diluent at the use site. For example, liquid detergents and cleaning solutions used for laundry and warewashing in hospitality locations, institutional or industrial installations such as hotels, hospitals, restaurants, and the like are often shipped as liquid concentrates that are mixed and diluted using a dispensing device at an appropriate ratio to obtain a useful solution.
The dilution of concentrates can be done in many ways, varying from, on one hand, simply manually measuring and mixing to utilizing a computer-controlled dilution device. One common dilution mode involves utilizing a dispensing device that combines, under mixing conditions, a flow of concentrate and a flow of diluent. The flow of the liquid diluent can be directed through an aspirator such that, as the diluent passes through the aspirator, a negative pressure arises inside the aspirator drawing the liquid concentrate into the aspirator to mix with the liquid diluent. Both Copeland et al., U.S. Pat. No. 5,033,649 and Freese, U.S. Pat. No. 4,817,825 and Mehus et al. U.S. Pat. No. 5,915,592 disclose dispensers having aspirators for diluting liquid concentrates to produce liquid products in this general way. Such aspirator-type dispensers have been used for diluting a liquid concentrate.
In a number of applications, it is desired to supply a certain amount of liquid concentrate. In using a timing mechanism wherein the aqueous diluent is used for a certain amount of time, various amounts of concentrate may be dispensed depending upon the pressure of the aqueous diluent.
The present invention addresses this problem and provides for a method and apparatus for delivering a more constant amount of product independent of the pressure of the source of the aqueous diluent.
In addition, the present invention addresses the need for a fail-safe design to prevent the generation of a poisonous gas if an acid and chlorine are mixed in the wrong proportions which may result in a build-up of a poisonous chlorine gas. It is common practice, due to product mixing, to use two lines to keep the chlorine line separate from an acid line.